\fQuestion 9: For given vectors, 5 = 2'13\" 2k and b = 4 +jk , find the unit vector in the direction of the vector E \"J \f\fQuestion 8: Find the unit vector in the direction of uectorPQ, where P and Q are the points; (1, 2, 3]- and (4, 5, 6), respectively. \f\f\f\f\f\f\f\f\f\f\fQ4: An eclge (If a variable cube is increasing at the rate [if 3 cmis. Haw fast is the ucnlume of the cube increasing 1when the edge is 1G cm long? \fQuestion 13: Find the direction cosines of the vector joining the points A (1, 2, 3) and B (1, 2, 1) directed from A to B. \f\f\fQuestion 19: If 5 and are two collinear vectors, then which of the following are incorrect: A. 5:35, for some scalar A B. (i = if; C. the respective components of '5 and 5 are proportional D. both the vectors '5 and b have same direction, but different magnitudes \f\f15. Question A binary operation * i5 defined an the Set R of all real numbers by the rule El .-::b = a: * b2 far all a, b E R. Write the identityr element for * an Ft. \f5f 5' ~ 2&7 Find a vector in the direction of vector which has magnitude 8 units. \f\f